Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Loans	$ 2,697,417,000	$ 2,558,552,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	5.40%
Commercial Portfolio Segment [Member]
Loans	$ 2,306,107,000	$ 2,203,568,000
Percent of portfolio	85.50%	86.10%
Period increase (decrease)	4.70%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 818,112,000	$ 753,764,000
Percent of portfolio	30.30%	29.40%
Period increase (decrease)	8.50%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 39,396,000	$ 29,873,000
Percent of portfolio	1.50%	1.20%
Period increase (decrease)	31.90%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 542,731,000	$ 526,328,000
Percent of portfolio	20.10%	20.60%
Period increase (decrease)	3.10%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 811,767,000	$ 791,685,000
Percent of portfolio	30.10%	30.90%
Period increase (decrease)	2.50%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 94,101,000	$ 101,918,000
Percent of portfolio	3.50%	4.00%
Period increase (decrease)	(7.70%)
Retail Portfolio Segment [Member]
Loans	$ 391,310,000	$ 354,984,000
Percent of portfolio	14.50%	13.90%
Period increase (decrease)	10.20%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 89,545,000	$ 100,425,000
Percent of portfolio	3.30%	3.90%
Period increase (decrease)	(10.80%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 301,765,000	$ 254,559,000
Percent of portfolio	11.20%	10.00%
Period increase (decrease)	18.50%
Originated Loan [Member]
Loans	$ 2,383,104,000	$ 2,169,957,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	9.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,090,476,000	$ 1,934,228,000
Percent of portfolio	87.70%	89.10%
Period increase (decrease)	8.10%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 766,159,000	$ 680,805,000
Percent of portfolio	32.10%	31.30%
Period increase (decrease)	12.50%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 33,714,000	$ 23,682,000
Percent of portfolio	1.40%	1.10%
Period increase (decrease)	42.40%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 490,130,000	$ 456,065,000
Percent of portfolio	20.60%	21.00%
Period increase (decrease)	7.50%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 737,316,000	$ 708,824,000
Percent of portfolio	30.90%	32.70%
Period increase (decrease)	4.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 63,157,000	$ 64,852,000
Percent of portfolio	2.70%	3.00%
Period increase (decrease)	(2.60%)
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 292,628,000	$ 235,729,000
Percent of portfolio	12.30%	10.90%
Period increase (decrease)	24.10%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 67,412,000	$ 69,675,000
Percent of portfolio	2.80%	3.20%
Period increase (decrease)	(3.20%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 225,216,000	$ 166,054,000
Percent of portfolio	9.50%	7.70%
Period increase (decrease)	35.60%
Acquired Loan [Member]
Loans	$ 314,313,000	$ 388,595,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(19.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 215,631,000	$ 269,340,000
Percent of portfolio	68.60%	69.30%
Period increase (decrease)	(19.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 51,953,000	$ 72,959,000
Percent of portfolio	16.50%	18.80%
Period increase (decrease)	(28.80%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 5,682,000	$ 6,191,000
Percent of portfolio	1.80%	1.60%
Period increase (decrease)	(8.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 52,601,000	$ 70,263,000
Percent of portfolio	16.70%	18.10%
Period increase (decrease)	(25.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 74,451,000	$ 82,861,000
Percent of portfolio	23.70%	21.30%
Period increase (decrease)	(10.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 30,944,000	$ 37,066,000
Percent of portfolio	9.90%	9.50%
Period increase (decrease)	(16.50%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 98,682,000	$ 119,255,000
Percent of portfolio	31.40%	30.70%
Period increase (decrease)	(17.30%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 22,133,000	$ 30,750,000
Percent of portfolio	7.00%	7.90%
Period increase (decrease)	(28.00%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 76,549,000	$ 88,505,000
Percent of portfolio	24.40%	22.80%
Period increase (decrease)	(13.50%)